This invention relates to an ink jet recording element, more particularly to a porous ink jet recording element.
In a typical ink jet recording or printing system, ink droplets are ejected from a nozzle at high speed towards a recording element or medium to produce an image on the medium. The ink droplets, or recording liquid, generally comprise a recording agent, such as a dye or pigment, and a large amount of solvent. The solvent, or carrier liquid, typically is made up of water, an organic material such as a monohydric alcohol, a polyhydric alcohol or mixtures thereof.
An ink jet recording element typically comprises a support having on at least one surface thereof an ink-receiving or image-forming layer. The ink-receiving layer may be a porous layer which imbibes the ink via capillary action or a polymer layer which swells to absorb the ink.
Ink jet prints, prepared by printing onto ink jet recording elements, are subject to environmental degradation. They are especially vulnerable to water smearing and light fade. For example, since ink jet dyes are water-soluble, they can migrate from their location in the image layer when water comes in contact with the receiver after imaging. Highly swellable hydrophilic layers can take an undesirably long time to dry, slowing printing speed, and will dissolve when left in contact with water, destroying printed images. Porous layers speed the absorption of the ink vehicle, but often suffer from insufficient gloss and severe light fade. Porous layers are also difficult to coat without cracking. The support for the ink receiving layers is typically either porous or non-porous. When it is porous, the support itself can absorb non-imaging ink components such as water, solvents, and humectants, so that the ink receiving layer thickness can be minimized. However, when the support itself is non-porous, the ink receiving layer thickness must be great enough to absorb all the ink rapidly in order to prevent degradation of the image by dye smear during printing.
EP 940,427 discloses a method for making a microporous film for an ink jet recording element in which a hydrophobic polymer and a second hydrophilic polymer or copolymer of N-vinylpyrrolidone is dissolved in a certain solvent system, partially dried, and then washed to extract at least 50% by weight of the second polymer. The amount of the hydrophobic polymer to the second hydrophilic polymer is stated as 2:1-1:3. This reference also discloses the addition of a mordant to the polymer mixture. However, this reference does not disclose the use of a fluid-absorbing layer, so that the element has a problem in that it has a limited ink-absorbing capacity.
U.S. Pat. Nos. 4,785,313 and 4,832,984 disclose a two-layer ink jet receiving element wherein the layer adjacent the support is an image receiving layer and the outermost layer is an ink-transporting layer. However, there is a problem with this receiving element due to the fact that the ink-retaining layer is underneath the ink-transporting layer, which would scatter light, thus lowering the optical density.
It is an object of this invention to provide an ink jet recording element which will provide improved ink uptake speed and capacity. Another object of the invention is to provide an ink jet recording element having a receiving layer that when printed upon has an excellent image quality. Still another object of the invention is to provide an ink jet recording element having a receiving layer wherein the printed image has improved water fastness. Yet still another object of the invention is to provide an ink jet recording element having improved ink absorbing capacity and drying rate when the support is non-porous or highly water resistant.
These and other objects are provided by the present invention comprising an ink jet recording element comprising a support having thereon in order:
a) a hydrophilic, fluid-absorbing layer, and
b) an image-receptive layer capable of retaining an ink jet image, the image-receptive layer comprising an open-pore membrane of a mixture of a water-insoluble polymer and a water-absorbent polymer, the mixture containing at least about 25% by weight of the water-absorbent polymer.
By use of the invention, a recording element is obtained which will provide improved ink uptake speed and capacity, and when printed upon, has an excellent image quality and improved water fastness.
In order for the image-receptive layer of the invention to be sufficiently porous, the water-insoluble polymer must be coated from a solvent mixture combination such that an open-pore membrane structure will be formed when the solution is coated and dried, in accordance with the known technique of dry phase inversion. In a preferred embodiment, the formation of an open-pore membrane is accomplished by using a mixture of a good and poor solvent for the water-insoluble polymer. In this embodiment, the poor solvent has a boiling point that is higher than that of the good solvent. When the solution is coated or cast onto a support and dried, the good solvent evaporates faster than the poor solvent, forming the membrane structure of the layer when the polymer phase separates from the solvent mixture. The open-pore structure results when the good solvent and poor solvent are removed by drying.
The water-insoluble polymer that can be used in the image-receptive layer of the invention may be, for example, a cellulose ester such as cellulose diacetate, cellulose triacetate, cellulose acetate propionate or cellulose acetate butyrate, cellulose nitrate, polyacrylates such as poly(methyl methacrylate), poly(phenyl methacrylate) and copolymers with acrylic or methacrylic acid, or sulfonates, polyesters, polyurethanes, polysulfones, urea resins, melamine resins, urea-formaldehyde resins, polyacetals, polybutyrals, epoxies and epoxy acrylates, phenoxy resins, polycarbonates, vinyl acetate polymers and copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-vinyl-alcohol copolymers, vinyl chloride-vinyl acetate-maleic acid polymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloride-acrylonitrile copolymers, acrylic ester-acrylonitrile copolymers, acrylic ester-vinylidene chloride copolymers, methacrylic ester-styrene copolymers, butadiene-acrylonitrile copolymers, acrylonitrile-butadiene-acrylic or methacrylic acid copolymers, or styrene-butadiene copolymers. Cellulose ester derivatives, such as cellulose diacetates and triacetates, cellulose acetate propionate, cellulose acetate butyrate, cellulose nitrate, and mixtures thereof are preferred.
The water-absorbent polymer that can be used in the image-receptive layer of the invention may be, for example, polyvinylpyrrolidone and vinylpyrrolidone-containing copolymers, polyethyloxazoline and oxazoline-containing copolymers, imidazole-containing polymers, polyacrylamides and acrylamide-containing copolymers, poly(vinyl alcohol) and vinyl-alcohol-containing copolymers, poly(vinyl methyl ether), poly(vinyl ethyl ether), poly(ethylene oxide), hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, methylcellulose, and mixtures thereof. As noted above, the water-absorbent polymer is present in an amount of at least about 25% by weight of the mixture. If the water-absorbent polymer is too high, for example, greater than about 75% by weight, then the open pore membrane structure is not formed. If the water-absorbent polymer is less than about 25% by weight, then poor image density is obtained.
The hydrophilic, fluid-absorbing layer useful in the invention may be gelatin, acetylated gelatin, phthalated gelatin, oxidized gelatin, chitosan, poly(alkylene oxide), a poly(vinyl alcohol), sulfonated polyester, partially hydrolyzed poly(vinyl acetate/vinyl alcohol), poly(acrylic acid), poly(1-vinyl pyrrolidone), poly(sodium styrene sulfonate), poly(2-acrylamido-2-methane sulfonic acid), polyacrylamide or mixtures thereof. In a preferred embodiment of the invention, the hydrophilic, fluid-absorbing layer is gelatin. In another preferred embodiment of the invention, the hydrophilic, fluid-absorbing layer is porous, comprising particulates such as an inorganic oxide or an organic polymer. For example, the porous, particulate-containing layer may be barium sulfate, calcium carbonate, clay, silica or alumina, or mixtures thereof.
In a preferred embodiment of the invention, the hydrophilic, fluid-absorbing layer has a thickness of about 1 xcexcm to about 40 xcexcm and the image-receptive layer has a thickness of about 2 xcexcm to about 50 xcexcm.
In another preferred embodiment of the invention, the image-receptive layer contains at least about 7% by weight of a mordant comprising a polymer or copolymer containing a quaternized nitrogen moiety. The mordant serves to improve the fixability of an ink jet image, thereby improving water fastness and smear. The mordant polymer can be a soluble polymer, or a crosslinked dispersed microparticle.
The mordant polymer or copolymer containing a quaternized nitrogen moiety which is useful in the invention can contain other comonomers such as, for example, styrenics, acrylates, imidazoles, vinylpyridines, etc. Examples of specific mordants include poly(styrene-co-1-vinylimidazole-co-1-vinyl-3-benzylimidazolium chloride), poly(styrene-co-1-vinylimidazole-co-1-vinyl-3-hydroxyethyl-imidazolium chloride), poly(styrene-co-1-vinylimidazole-co-1-vinyl-3-benzylimidazolium chloride-co-1-vinyl-3-hydroxyethylimidazolium chloride), poly(vinylbenzyltrimethylammonium chloride-co-divinylbenzene), poly(ethyl acrylate-co-1-vinylimidazole-co-1-vinyl-3-benzylimidazolium chloride), or poly(styrene-co-4-vinylpyridine-co-4-hydroxyethyl-1-vinylpyridinium chloride).
In a preferred embodiment of the invention, the quaternary nitrogen moiety is a salt of trimethylvinylbenzylammonium, benzyldimethyl-vinylbenzylammonium, dimethyloctadecylvinylbenzylammonium, 1-vinyl-3-benzylimidazolium, 1-vinyl-3-hydroxyethylimidazolium or 4-hydroxyethyl 1-vinylpyridinium. Preferred counter ions which can be used include chlorides or other counter ions as disclosed in U.S. Pat. Nos. 5,223,338; 5,354,813; and 5,403,955, the disclosures of which are hereby incorporated by reference. The hydrophilic, fluid-absorbing layer useful in the invention may also contain mordant polymers.
The choice of a good and poor solvent for the water-insoluble polymer will be effectively determined by the specific choice of polymer. The good solvent that can be used in the invention includes alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, isobutyl alcohol, Dowanol(copyright) solvents, glycols, ketones such as acetone, 2-butanone, 3-pentanone, cyclopentanone, and cyclohexanone, ethyl acetate, methylacetoacetate, diethylether, tetrahydrofuran, acetonitrile, dimethylformamide, dimethylsulfoxide, pyridine, chlorinated solvents such as methylene chloride, chloroform, carbon tetrachloride, and dichloroethane, hexane, heptane, cyclopentane, cyclohexane, toluene, xylenes, nitrobenzene, and mixtures thereof.
The poor solvent that can be used in the invention may be, for example, alcohols such as ethanol, n-propyl alcohol, isopropyl alcohol, isobutyl alcohol, 2-methyl-2,4-pentanediol, and Dowanol(copyright) solvents, glycols, ketones such as 2-butanone, 3-pentanone, cyclopentanone, and cyclohexanone, ethyl acetate, methylacetoacetate, diethylether, tetrahydrofuran, acetonitrile, dimethylformamide, dimethylsulfoxide, pyridine, chlorinated solvents such as carbon tetrachloride, and dichloroethane, hexane, heptane, cyclopentane, cyclohexane, toluene, xylenes, nitrobenzene, water, and mixtures thereof.
Since the image recording element may come in contact with other image recording articles or the drive or transport mechanisms of image recording devices, additives such as filler particles, surfactants, lubricants, crosslinking agents, matte particles and the like may be added to the element to the extent that they do not degrade the properties of interest.
Filler particles may be used in the open-pore membrane, the hydrophilic, fluid-absorbing layer, or both. Examples of filler particles are silicon oxide, fumed silica, silicon oxide dispersions such as those available from Nissan Chemical Industries and DuPont Corp., aluminum oxide, fumed alumina, calcium carbonate, barium sulfate, barium sulfate mixtures with zinc sulfide, inorganic powders such as xcex3-aluminum oxide, chromium oxide, iron oxide, tin oxide, doped tin oxide, alumino-silicate, titanium dioxide, natural or synthetic clay particles, organic particles, such as polystyrene matte beads, highly crosslinked organic polymer particles derived primarily from styrene, acrylates, or methacrylates, mixtures of these monomers, or mixtures with other monomers.
A dispersing agent, or wetting agent can be present to facilitate the dispersion of the filler particles. This helps to minimize the agglomeration of the particles. Useful dispersing agents include, but are not limited to, fatty acid amines and commercially available wetting agents such as Solsperse(copyright) sold by Zeneca, Inc. (ICI). Preferred filler particles are silicon oxide, aluminum oxide, calcium carbonate, and barium sulfate. Preferably, these filler particles have a median diameter less than 1.0 xcexcm. The filler particles can be present in the amount from about 0 to 80 percent of the total solids in the dried open-pore membrane layer, most preferably in the amount from about 0 to 40 percent.
The open-pore membrane layer, the hydrophilic, fluid-absorbing layer, or both, may include lubricating agents. Lubricants and waxes useful either in the open-pore membrane layer or on the side of the element that is opposite the open-pore membrane layer include, but are not limited to, polyethylenes, silicone waxes, natural waxes such as carnauba, polytetrafluoroethylene, fluorinated ethylene propylene, silicone oils such as polydimethylsiloxane, fluorinated silicones, functionalized silicones, stearates, polyvinylstearate, fatty acid salts, and perfluoroethers. Aqueous or non-aqueous dispersions of submicron size wax particles such as those offered commercially as dispersions of polyolefins, polypropylene, polyethylene, high density polyethylene, microcrystalline wax, paraffin, natural waxes such as carnauba wax, and synthetic waxes from such companies as, but not limited to, Chemical Corporation of America (Chemcor), Inc., Michelman Inc., Shamrock Technologies Inc., and Daniel Products Company, are useful.
The open-pore membrane layer, the hydrophilic, fluid-absorbing layer, or both, may include coating aids and surfactants such as nonionic fluorinated alkyl esters such as FC-430(copyright), FC-431(copyright), FC-10(copyright), FC-171(copyright) sold by Minnesota Mining and Manufacturing Co., Zonyl(copyright) fluorochemicals such as Zonyl-FSN(copyright), Zonyl-FTS(copyright), Zonyl-TBS(copyright), Zonyl-BA(copyright) sold by DuPont Corp.; other fluorinated polymer or copolymers such as Modiper F600(copyright) sold by NOF Corporation, polysiloxanes such as Dow Corning DC 1248(copyright), DC200(copyright), DC510(copyright), DC 190(copyright) and BYK 320(copyright), BYK 322(copyright), sold by BYK Chemie and SF 1079(copyright), SF1023(copyright), SF 1054(copyright), and SF 1080(copyright) sold by General Electric, and the Silwet(copyright) polymers sold by Union Carbide; polyoxyethylene-lauryl ether surfactants; sorbitan laurate, palmitate and stearates such as Span(copyright) surfactants sold by Aldrich; poly(oxyethylene-co-oxypropylene) surfactants such as the Pluronic(copyright) family sold by BASF; and other polyoxyethylene-containing surfactants such as the Triton X(copyright) family sold by Union Carbide, ionic surfactants, such as the Alkanol(copyright) series sold by DuPont Corp., and the Dowfax(copyright) family sold by Dow Chemical.
The open-pore membrane layer, the hydrophilic, fluid-absorbing layer, or both, may include crosslinking agents, such as organic isocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, diisocyanato dimethylcyclohexane, dicyclohexylmethane diisocyanate, isophorone diisocyanate, dimethylbenzene diisocyanate, methylcyclohexylene diisocyanate, lysine diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate; aziridines such as taught in U.S. Pat. No. 4,225,665; ethyleneimines such as Xama-7(copyright) sold by EIT Industries; blocked isocyanates such as CA BI-12 sold by Cytec Industries; melamines such as methoxymethyhnelamine as taught in U.S. Pat. No. 5,198,499; alkoxysilane coupling agents including those with epoxy, amine, hydroxyl, isocyanate, or vinyl functionality; Cymel(copyright) crosslinking agents such as Cymel 300(copyright), Cymel 303(copyright), Cymel 1170(copyright), Cymel 1171(copyright) sold by Cytec Industries; and bis-epoxides such as the Epon(copyright) family sold by Shell. Other crosslinking agents include compounds such as aryloylureas, aldehydes, dialdehydes and blocked dialdehydes, chlorotriazines, carbamoyl pyridiniums, pyridinium ethers, formamidinium ethers, and vinyl sulfones. Such crosslinking agents can be low molecular weight compounds or polymers, as discussed in U.S. Pat. No. 4,161,407 and references cited.
In the present invention, the support can be either transparent or opaque. Opaque supports include plain paper, coated paper, synthetic paper, photographic paper support, melt-extrusion-coated paper, and laminated paper, such as biaxially oriented support laminates. Biaxially oriented support laminates are described in U.S. Pat. Nos. 5,853,965; 5,866,282; 5,874,205; 5,888,643; 5,888,681; 5,888,683; and 5,888,714, the disclosures of which are hereby incorporated by reference. These biaxially oriented supports include a paper base and a biaxially oriented polyolefin sheet, typically polypropylene, laminated to one or both sides of the paper base. Transparent supports include glass, cellulose derivatives, e.g., a cellulose ester, cellulose triacetate, cellulose diacetate, cellulose acetate propionate, cellulose acetate butyrate; polyesters, such as polyethylene terephthalate, polyethylene naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, polybutylene terephthalate, and copolymers thereof; polyimides; polyamides; polycarbonates; polystyrene; polyolefins, such as polyethylene or polypropylene; polysulfones; polyacrylates; polyether imides; and mixtures thereof. The papers listed above include a broad range of papers, from high end papers, such as photographic paper to low end papers, such as newsprint.
The support used in the invention may employ an undercoat or an adhesive layer such as, for example, a vinylidene chloride-methyl acrylate-itaconic acid terpolymer or a vinylidene chloride-acrylonitrile-acrylic acid terpolymer. Other chemical adhesives, such as polymers, copolymers, reactive polymers or copolymers, that exhibit good bonding between the hydrophilic, fluid-absorbing layer and the support can be used. Other methods to improve the adhesion of the layer to the support include surface treatment such as by coronadischarge, plasma-treatment in a variety of atmospheres, UV treatment, etc, which is performed prior to applying the layer to the support.
The recording element of the invention can contain one or more conducting layers such as an antistatic layer to prevent undesirable static discharges during manufacture and printing of the image. This may be added to either side of the element. Antistatic layers conventionally used for color films have been found to be satisfactory, such as those in U.S. Pat. No. 5,147,768, the disclosure of which is hereby incorporated by reference. Preferred antistatic agents include metal oxides, e.g., tin oxide, antimony doped tin oxide and vanadium pentoxide. These antistatic agents are preferably dispersed in a film-forming binder.
The layers described above may be coated by conventional coating means onto a support material commonly used in this art. Coating methods may include, but are not limited to, wound wire rod coating, knife coating, slot coating, slide hopper coating, gravure coating, spin coating, dip coating, skim-pan-air-knife coating, multilayer slide bead, blade coating, curtain coating, multilayer curtain coating and the like. Some of these methods allow for simultaneous coatings of more than one layer, which is preferred from a manufacturing economic perspective if more than one layer or type of layer needs to be applied. The support may be stationary, or may be moving so that the coated layer is immediately drawn into drying chambers.
Ink jet inks used to image the recording elements of the present invention are well known in the art. The ink compositions used in ink jet printing typically are liquid compositions comprising a solvent or carrier liquid, dyes or pigments, humectants, organic solvents, detergents, thickeners, preservatives, and the like. The solvent or carrier liquid can be solely water or can be water mixed with other water-miscible solvents such as polyhydric alcohols. Inks in which organic materials such as polyhydric alcohols are the predominant carrier or solvent liquid may also be used. Particularly useful are mixed solvents of water and polyhydric alcohols. The dyes used in such compositions are typically water-soluble direct or acid type dyes. Such liquid compositions have been described extensively in the prior art including, for example, U.S. Pat. Nos. 4,381,946; 4,239,543 and 4,781,758, the disclosures of which are hereby incorporated by reference.
Although the recording elements disclosed herein have been referred to primarily as being useful for ink jet printers, they also can be used as recording media for pen plotter assemblies. Pen plotters operate by writing directly on the surface of a recording medium using a pen consisting of a bundle of capillary tubes in contact with an ink reservoir.
The following examples further illustrate the invention.